1. Field of the Invention
The present invention relates in general to automotive lamp assemblies, and more particularly, to automotive lamp assemblies of a type which is constructed to eliminate or at least minimize a collection of moisture on surfaces of the lens and reflector installed in the lamp assembly.
2. Description of the Prior Art
In lamp assemblies, particularly in automotive headlamp assemblies, a considerable change of temperature is produced in the interior thereof between ON and OFF conditions of the lamp bulb installed therein. However, such temperature change induces a collection of moisture on inner surfaces of the lens and reflector in the assembly due to a trace of water inevitably contained in the assembly. The collected moisture causes deterioration in not only reflection of the light on the reflector but also transmission of the light through the lens.
Thus, hitherto, various attempts have been made for eliminating such undesirable moisture collection phenomenon of the lamp assembly. One of them is to provide the lamp assembly with a hermetically sealed construction to shut out water. However, it is quite difficult and expensive to produce a lamp assembly which can completely shut out the water.
In view of the above, a so-called "ventilation type assembly" has been proposed, which is constructed to permit flowing of the outside air through the interior of the assembly. In this type lamp assembly, inlet and outlet pipes are connected to the lamp assembly to provide a ventilation passage through the interior of the lamp assembly, and the air in the passage is forced to flow therethrough by force of convection of air in the assembly, which convection is created by heat generated by the electric bulb under energization. However, even in the lamp assemblies of this type, satisfactory performance has not been obtained due to the inherency in construction thereof.